This invention relates to a dash panel structure for an automobile including a deployment opening for an underlying inflatable air bag cushion. More particularly, the invention relates to a method of forming a deployment opening within a dash panel structure such that the deployment opening is not visible to an occupant viewing the exterior of the dash panel structure.
It is well known in motor vehicles to provide an air bag module which includes an inflatable air bag cushion for the protection of a vehicle occupant in the event of a collision. The air bag module typically includes an inflator for discharging an inflation medium such as high pressure gas or the like into the air bag cushion upon the occurrence of a predetermined level of vehicle deceleration or other measurable vehicle condition.
Inflatable air bag cushions may be disposed at a number of locations within the vehicle so as to provide protection for the occupants therein during various collision events. In particular, it is known to utilize an inflatable air bag cushion stored within the hub of the steering wheel for protection of the operator of the vehicle and to utilize an inflatable air bag cushion deployable from the dash panel for protection of a passenger within the vehicle during a collision event. In order to facilitate the deployment of inflatable air bag cushions from the dash panel, it is known to incorporate a pattern across the surface of the dash panel which preferentially tears to form a defined deployment opening pattern across the surface of the dash panel as the air bag cushion is inflated. The creation of such a pattern across the surface of the dash panel typically leads to visible seams across the surface of the dash panel at the location of the deployment opening pattern. The presence of such visible seams may detract from the aesthetic character of the dash panel and may thus be viewed as undesirable by some users.
In order to address the desire to conceal the deployment opening pattern from the occupants within the vehicle, it has been proposed to cover the dash panel with an outer skin layer the underside of which is scored in a pattern corresponding to the desired deployment opening pattern and thereafter apply a layer of foam across the scored surface so as to provide a layer of continuous support to the scored surface. A substrate panel which may include deployment opening doors disposed over the inflatable air bag is provided beneath the foam support layer. As will be appreciated, such a construction requires the separate formation of the skin and the underlying support structure of the foam and substrate panel as well as a separate formation step for forming deployment opening doors within the substrate panel. Moreover, due to the fact that there are separately formed deployment opening patterns within the substrate panel and the outer skin which are separated by a substantially continuous layer of uninterrupted foam, the establishment of a substantially aligned opening pattern between the substrate panel and the skin may be difficult to achieve. The failure to establish a fully aligned opening pattern between the substrate panel and the skin may require the application of additional force by the air bag cushion in order to exit the dash panel.
The present invention provides advantages and alternatives over the prior art by providing a dash panel structure having a hidden deployment opening formed beneath the surface of the dash panel structure wherein a substrate panel is weakened in a desired pattern by cutting through the substrate panel and at least partially into the foam or other cushioning material overlying the substrate panel in a pattern substantially corresponding to a deployment opening pattern of grooved construction extending across the inner surface of a skin layer at the exterior of the dash panel structure. The patterned weakening of the substrate panel and overlying foam corresponding to the deployment opening pattern in the skin permits the efficient deployment of an underlying air bag without the application of undue force. Moreover, due to the fact that the foam is also at least partially cut, foam fragmentation is reduced which is believed to substantially prevent the potentially undesired outward projection of foam fragments during deployment of the air bag.
These advantages are accomplished in a potentially preferred form of the invention by providing a dash panel structure having an outer skin layer overlying a layer of foam cushioning material with a dimensionally stable support panel disposed below the cushioning material. A break-out pattern of slotted configuration is applied across the surface of the substrate panel and at least partially into the overlying foam in a pattern substantially corresponding to the desired deployment path of an underlying air bag cushion. The break-out pattern formed across the substrate panel is substantially aligned with a corresponding deployment opening pattern of grooved construction extending across the inner surface of the skin layer such that the deployment of the air bag cushion may be carried out at a controlled defined location within the dash panel structure.
According to a potentially preferred feature of the present invention, it is contemplated that the deployment opening pattern across the inner surface of the skin layer may be formed simultaneously with the formation of the break-out pattern across the support panel using a single cutting operation.
In accordance with another potentially preferred aspect of the present invention, it is contemplated that the deployment opening pattern across the skin layer may be substantially continuous in character while the break-out pattern across the substrate panel may be formed from a plurality of slots separated one from the other by uncut tabs. It is further contemplated that the continuous groove across the inner surface of the skin layer may be formed simultaneously with the slots across the substrate panel by use of a variable angle material removal device.
According to yet a further feature of the present invention, it is contemplated that the deployment opening pattern across the skin layer may be formed separately from the formation of the break-out pattern across the substrate panel and foam layer.